1. Grade 3 Mental Math Subtraction – Fact Learning

2. C: Subtraction – Fact Learning Strategies There are 4 subtraction fact Learning strategies: –Think Addition (Extension) –Quick Counting Back (New) –Back Through 10 (New) –Up Through 10 (New)

3. Think Addition Strategy (Introduction) In this strategy students rely on their knowledge of addition facts. –Ex. Double Facts, Plus 1 Facts, Plus 2 facts, Near Double facts etc. They know that certain numbers added together equal a certain number. Ex. 4 + 3 = 7 or 3 + 4 = 7 (a near double fact) The strategy involves think: what number added to the subtrahend gives the minuend

4. Think Addition Example (Introduction) For 7 – 1: think what number added to 1 gives 6. Remember the addition fact 6 + 1 = 7. So the answer is 6 For 15 – 6: think what number added to 6 gives 15. Remember that 9 + 6 = 15. So the answer is 9

5. Think Addition Reinforcement (Day 1) Question # 1 8 – 4 =

6. Think Addition Reinforcement (Day 1 cont.) Answer:

7. Think Addition Reinforcement (Day 1 cont.) Question # 2 6 take away 3 is

8. Think Addition Reinforcement (Day 1 cont.) Answer:

9. Think Addition Reinforcement (Day 1 cont.) Question # 3 7 days less than 14 days is how many days?

10. Think Addition Reinforcement (Day 1 cont.) Answer:

11. End of Lesson

12. Think Addition Reinforcement (Day 2) Question # 1 $15 - $8 is

13. Think Addition Reinforcement (Day 2 cont.) Answer:

14. Think Addition Reinforcement (Day 2 cont.) Question # 2 16 children are 9 boys and how many girls?

15. Think Addition Reinforcement (Day 2 cont.) Answer:

16. Think Addition Reinforcement (Day 2 cont.) Question # 3 –2 cm less than 6 cm is

17. Think Addition Reinforcement (Day 2 cont.) Answer:

18. Think Addition Reinforcement (Day 2 cont.) Question # 4 The difference between 8 kg and 1 kg is how many kg?

19. Think Addition Reinforcement (Day 2 cont.) Answer:

20. Think Addition Reinforcement (Day 2 cont.) Question # 5 5 apples out of 10 apples were eaten. How many apples remain?

21. Think Addition Reinforcement (Day 2 cont.) Answer:

22. End of Lesson

23. Think Addition Reinforcement (Day 3) Question # 1 9 – 7 =

24. Think Addition Reinforcement (Day 3 cont.) Answer:

25. Think Addition Reinforcement (Day 3 cont.) Question # 2 13 minus 6 is

26. Think Addition Reinforcement (Day 3 cont.) Answer:

27. Think Addition Reinforcement (Day 3 cont.) Question # 3 9 fewer than 15

28. Think Addition Reinforcement (Day 3 cont.) Answer:

29. Think Addition Reinforcement (Day 3 cont.) Question # 4 18 cm take away 10 cm

30. Think Addition Reinforcement (Day 3 cont.) Answer:

31. Think Addition Reinforcement (Day 3 cont.) Question # 5 7 birds and 2 fly away. How many remain?

32. Think Addition Reinforcement (Day 3 cont.) Answer:

33. End of Lesson

34. Think Addition Reinforcement (Day 4) Question # 1 8 – 0 =

35. Think Addition Reinforcement (Day 4 cont.) Answer:

36. Think Addition Reinforcement (Day 4 cont.) Question # 2 $9 less than $14 is how much?

37. Think Addition Reinforcement (Day 4 cont.) Answer:

38. Think Addition Reinforcement (Day 4 cont.) Question # 3 The difference between 9 and 7

39. Think Addition Reinforcement (Day 4 cont.) Answer:

40. Think Addition Reinforcement (Day 4 cont.) Question # 4 8 L of water was at the game. The players drank 4 L. How much water is left?

41. Think Addition Reinforcement (Day 4 cont.) Answer:

42. Think Addition Reinforcement (Day 4 cont.) Question # 5 10 - ____ = 8

43. Think Addition Reinforcement (Day 4 cont.) Answer:

44. End of Lesson

45. Think Addition Assessment (Day 5) Question # 1 7 less 5

46. Think Addition Assessment (Day 5 cont.) Answer:

47. Think Addition Assessment (Day 5 cont.) Question # 2 12 minus 8

48. Think Addition Assessment (Day 5 cont.) Answer:

49. Think Addition Assessment (Day 5 cont.) Question # 3 6 fewer than 9

50. Think Addition Assessment (Day 5 cont.) Answer:

51. Think Addition Assessment (Day 5 cont.) Question # 4 How much time passes between 4 o’clock and 12 o’clock?

52. Think Addition Assessment (Day 5 cont.) Answer:

53. Think Addition Assessment (Day 5 cont.) Question # 5 15 pencils. 9 are dull. How many are sharp?

54. Think Addition Assessment (Day 5 cont.) Answer:

55. End of Lesson

56. Quick Counting Back Strategy (Introduction) In this strategy students count back the smaller number from the larger number This strategy should only be used when subtracting 1, 2, or 3 The counting back should be done quickly in the head and not on the fingers

57. Quick Counting Back Example (Introduction) For 9 – 2: think 9 counting back 2 is 8, 7. So the answer is 7 For 8 – 3: think 8 counting back 3 is 7, 6, 5. So the answer is 5. For 6 – 1: think 6 counting back 1 is 5. So the answer is 5.

58. Quick Counting Back Reinforcement (Day 1) Question # 1 7 – 1 =

59. Quick Counting Back Reinforcement (Day 1 cont.) Answer:

60. Quick Counting Back Reinforcement (Day 1 cont.) Question # 2 8 less 2 equals

61. Quick Counting Back Reinforcement (Day 1 cont.) Answer:

62. Quick Counting Back Reinforcement (Day 1 cont.) Question # 3 6 minus 3 is:

63. Quick Counting Back Reinforcement (Day 1 cont.) Answer:

64. End of Lesson

65. Quick Counting Back Reinforcement (Day 2) Question # 1 8 kg less 2 kg is how many kg?

66. Quick Counting Back Reinforcement (Day 2 cont.) Answer:

67. Quick Counting Back Reinforcement (Day 2 cont.) Question # 2 $9 - $3 =

68. Quick Counting Back Reinforcement (Day 2 cont.) Answer:

69. Quick Counting Back Reinforcement (Day 2 cont.) Question # 3 The difference between 7 and 2

70. Quick Counting Back Reinforcement (Day 2 cont.) Answer:

71. Quick Counting Back Reinforcement (Day 2 cont.) Question # 4 One lass than 5

72. Quick Counting Back Reinforcement (Day 2 cont.) Answer:

73. Quick Counting Back Reinforcement (Day 2 cont.) Question # 5 7 take away 2

74. Quick Counting Back Reinforcement (Day 2 cont.) Answer:

75. End of Lesson

76. Quick Counting Back Reinforcement (Day 3) Question # 1 7 – 3 =

77. Quick Counting Back Reinforcement (Day 3 cont.) Answer:

78. Quick Counting Back Reinforcement (Day 3 cont.) Question # 2 8 candies were on the table and 3 were eaten. How many remain?

79. Quick Counting Back Reinforcement (Day 3 cont.) Answer:

80. Quick Counting Back Reinforcement (Day 3 cont.) Question # 3 The difference between 9 cm and 2 cm

81. Quick Counting Back Reinforcement (Day 3 cont.) Answer:

82. Quick Counting Back Reinforcement (Day 3 cont.) Question # 4 10 less 3

83. Quick Counting Back Reinforcement (Day 3 cont.) Answer:

84. Quick Counting Back Reinforcement (Day 3 cont.) Question # 5 12 – 1 =

85. Quick Counting Back Reinforcement (Day 3 cont.) Answer:

86. End of Lesson

87. Quick Counting Back Reinforcement (Day 4) Question # 1 One less than 13

88. Quick Counting Back Reinforcement (Day 4 cont.) Answer:

89. Quick Counting Back Reinforcement (Day 4 cont.) Question # 2 Two less than 11

90. Quick Counting Back Reinforcement (Day 4 cont.) Answer:

91. Quick Counting Back Reinforcement (Day 4 cont.) Question # 3 14 minus 3 is:

92. Quick Counting Back Reinforcement (Day 4 cont.) Answer:

93. Quick Counting Back Reinforcement (Day 4 cont.) Question # 4 8 cm reduced by 3 cm

94. Quick Counting Back Reinforcement (Day 4 cont.) Answer:

95. Quick Counting Back Reinforcement (Day 4 cont.) Question # 5 6 – 1 =

96. Quick Counting Back Reinforcement (Day 4 cont.) Answer:

97. End of Lesson

98. Quick Counting Back Assessment (Day 5) Question # 1 Two less than 18

99. Quick Counting Back Assessment (Day 5 cont.) Answer:

100. Quick Counting Back Assessment (Day 5 cont.) Question # 2 The difference between 16 and 3 is

101. Quick Counting Back Assessment (Day 5 cont.) Answer:

102. Quick Counting Back Assessment (Day 5 cont.) Question # 3 9 minus 2

103. Quick Counting Back Assessment (Day 5 cont.) Answer:

104. Quick Counting Back Assessment (Day 5 cont.) Question # 4 13 take away 3

105. Quick Counting Back Assessment (Day 5 cont.) Answer:

106. Quick Counting Back Assessment (Day 5 cont.) Question # 5 3 less than 14

107. Quick Counting Back Assessment (Day 5 cont.) Answer:

108. End of Lesson

109. Back Through 10 Strategy (Introduction) This strategy is used when the minuend is greater than 10 Students subtract the subtrahend from thee minuend in 2 steps –1) to get to 10 –2) take away the rest from 10 Modelling this strategy on a number line will provide students with a good visual for example: 14 – 6. Take away 4 to get 10 and take 2 more to get 8

110. Back Through 10 Example (Introduction) For 15 – 6: think to take 6 from 15 first take 5 to get to 10 and the take 1 more (the rest of 6) to get to 9. For 12 – 5: think to take 5 from 12 first take 2 to get to 10 and then take 3 (the rest of 5) to get 7

111. Back Through 10 Reinforcement (Day 1) Question # 1 14 – 9 =

112. Back Through 10 Reinforcement (Day 1 cont.) Answer:

113. Back Through 10 Reinforcement (Day 1 cont.) Question # 2 4 less than 11

114. Back Through 10 Reinforcement (Day 1 cont.) Answer:

115. Back Through 10 Reinforcement (Day 1 cont.) Question # 3 16 subtract 7

116. Back Through 10 Reinforcement (Day 1 cont.) Answer:

117. End of Lesson

118. Back Through 10 Reinforcement (Day 2) Question # 1 The difference between $6 and $13

119. Back Through 10 Reinforcement (Day 2 cont.) Answer:

120. Back Through 10 Reinforcement (Day 2 cont.) Question # 2 17 questions and 9 correct. How many incorrect?

121. Back Through 10 Reinforcement (Day 2 cont.) Answer:

122. Back Through 10 Reinforcement (Day 2 cont.) Question # 3 15 – 7 =

123. Back Through 10 Reinforcement (Day 2 cont.) Answer:

124. Back Through 10 Reinforcement (Day 2 cont.) Question # 4 14 minus 8 is

125. Back Through 10 Reinforcement (Day 2 cont.) Answer:

126. Back Through 10 Reinforcement (Day 2 cont.) Question # 5 3 less than 12

127. Back Through 10 Reinforcement (Day 2 cont.) Answer:

128. End of Lesson

129. Back Through 10 Reinforcement (Day 3) Question # 1 The difference between 9 and 16

130. Back Through 10 Reinforcement (Day 3 cont.) Answer:

131. Back Through 10 Reinforcement (Day 3 cont.) Question # 2 How much less is 8 km than 14 km?

132. Back Through 10 Reinforcement (Day 3 cont.) Answer:

133. Back Through 10 Reinforcement (Day 3 cont.) Question # 3 17 – 9 =

134. Back Through 10 Reinforcement (Day 3 cont.) Answer:

135. Back Through 10 Reinforcement (Day 3 cont.) Question # 4 16 minus 7 is:

136. Back Through 10 Reinforcement (Day 3 cont.) Answer:

137. Back Through 10 Reinforcement (Day 3 cont.) Question # 5 The difference between 5 and 13

138. Back Through 10 Reinforcement (Day 3 cont.) Answer:

139. End of Lesson

140. Back Through 10 Reinforcement (Day 4) Question # 1 Subtract 4 from 12

141. Back Through 10 Reinforcement (Day 4 cont.) Answer:

142. Back Through 10 Reinforcement (Day 4 cont.) Question # 2 7 less than 15

143. Back Through 10 Reinforcement (Day 4 cont.) Answer:

144. Back Through 10 Reinforcement (Day 4 cont.) Question # 3 17 – 9 =

145. Back Through 10 Reinforcement (Day 4 cont.) Answer:

146. Back Through 10 Reinforcement (Day 4 cont.) Question # 4 You had 15 cookies and ate 7. How many remain?

147. Back Through 10 Reinforcement (Day 4 cont.) Answer:

148. Back Through 10 Reinforcement (Day 4 cont.) Question # 5 16 minus 8

149. Back Through 10 Reinforcement (Day 4 cont.) Answer:

150. End of Lesson

151. Back Through 10 Assessment (Day 5) Question # 1 15 – 9 =

152. Back Through 10 Assessment (Day 5 cont.) Answer:

153. Back Through 10 Assessment (Day 5 cont.) Question # 2 The difference between 8 and 14

154. Back Through 10 Assessment (Day 5 cont.) Answer:

155. Back Through 10 Assessment (Day 5 cont.) Question # 3 6 less than 13

156. Back Through 10 Assessment (Day 5 cont.) Answer:

157. Back Through 10 Assessment (Day 5 cont.) Question # 4 9 taken from 16

158. Back Through 10 Assessment (Day 5 cont.) Answer:

159. Back Through 10 Assessment (Day 5 cont.) Question # 5 14 – 8 =

160. Back Through 10 Assessment (Day 5 cont.) Answer:

161. End of Lesson

162. Up Through 10 Strategy (Introduction) This strategy is used when the minuend is greater than 10 It is done by make two calculations: –1) the difference between 10 and the subtrahend –2) the difference between the minuend and 10 These 2 differences are then added together

163. Up Through 10 Example (Introduction) For 12 – 9, think: From 9 to 10 is 1, and from 10 to 12 is 2, so the total difference is 1 plus 2, or 3. In symbols: 12 – 9 = (10 – 9) + (12 – 10) = 1 + 2 = 3 For 14 – 8, think: From 8 to 10 is 2, and from 10 to 14 is 4, so the total difference is 2 plus 4, or 6. In symbols: 14 – 8 = (10 – 8) + (14 – 10) = 2 + 4 = 6

164. Up Through 10 Reinforcement (Day 1) Question # 1 8 less than 14

165. Up Through 10 Reinforcement (Day 1 cont.) Answer:

166. Up Through 10 Reinforcement (Day 1 cont.) Question # 2 $13 minus $9

167. Up Through 10 Reinforcement (Day 1 cont.) Answer:

168. Up Through 10 Reinforcement (Day 1 cont.) Question # 3 12 - 8 =

169. Up Through 10 Reinforcement (Day 1 cont.) Answer:

170. End of Lesson

171. Up Through 10 Reinforcement (Day 2) Question # 1 The difference between 9 and 11

172. Up Through 10 Reinforcement (Day 2 cont.) Answer:

173. Up Through 10 Reinforcement (Day 2 cont.) Question # 2 8 km less than 13 km

174. Up Through 10 Reinforcement (Day 2 cont.) Answer:

175. Up Through 10 Reinforcement (Day 2 cont.) Question # 3 9 subtracted from 14

176. Up Through 10 Reinforcement (Day 2 cont.) Answer:

177. Up Through 10 Reinforcement (Day 2 cont.) Question # 4 15 – 8 =

178. Up Through 10 Reinforcement (Day 2 cont.) Answer:

179. Up Through 10 Reinforcement (Day 2 cont.) Question # 5 13 minus 8

180. Up Through 10 Reinforcement (Day 2 cont.) Answer:

181. End of Lesson

182. Up Through 10 Reinforcement (Day 3 ) Question # 1 14 students and 9 are boys. How many girls?

183. Up Through 10 Reinforcement (Day 3 cont.) Answer:

184. Up Through 10 Reinforcement (Day 3 cont.) Question # 2 15 take away 8

185. Up Through 10 Reinforcement (Day 3 cont.) Answer:

186. Up Through 10 Reinforcement (Day 3 cont.) Question # 3 8 less than 14

187. Up Through 10 Reinforcement (Day 3 cont.) Answer:

188. Up Through 10 Reinforcement (Day 3 cont.) Question # 4 How much is 9 cents less than 13 cents

189. Up Through 10 Reinforcement (Day 3 cont.) Answer:

190. Up Through 10 Reinforcement (Day 3 cont.) Question # 5 8 fewer than 12 is:

191. Up Through 10 Reinforcement (Day 3 cont.) Answer:

192. End of Lesson

193. Up Through 10 Reinforcement (Day 4) Question # 1 16 – 9 =

194. Up Through 10 Reinforcement (Day 4 cont.) Answer:

195. Up Through 10 Reinforcement (Day 4 cont.) Question # 2 15 minus 8

196. Up Through 10 Reinforcement (Day 4 cont.) Answer:

197. Up Through 10 Reinforcement (Day 4 cont.) Question # 3 8 metes less than 13 meters

198. Up Through 10 Reinforcement (Day 4 cont.) Answer:

199. Up Through 10 Reinforcement (Day 4 cont.) Question # 4 16 pets and 8 are dogs. How many are cats?

200. Up Through 10 Reinforcement (Day 4 cont.) Answer:

201. Up Through 10 Reinforcement (Day 4 cont.) Question # 5 9 less than 15

202. Up Through 10 Reinforcement (Day 4 cont.) Answer:

203. End of Lesson

204. Up Through 10 Assessment (Day 5) Question # 1 14 – 9 =

205. Up Through 10 Assessment (Day 5 cont.) Answer:

206. Up Through 10 Assessment (Day 5 cont.) Question # 2 15 minus 8 is:

207. Up Through 10 Assessment (Day 5 cont.) Answer:

208. Up Through 10 Assessment (Day 5 cont.) Question # 3 What is 8 km fewer than 14 km?

209. Up Through 10 Assessment (Day 5 cont.) Answer:

210. Up Through 10 Assessment (Day 5 cont.) Question # 4 How much less is 9 than 13?

211. Up Through 10 Assessment (Day 5 cont.) Answer:

212. Up Through 10 Assessment (Day 5 cont.) Question # 5 9 subtracted from 16 is:

213. Up Through 10 Assessment (Day 5 cont.) Answer:

214. End of Lesson

215. Subtraction – Fact Learning Summative Assessment (Day 1) Question # 1 7 days less than 14 days is how many days?

216. Subtraction – Fact Learning Summative Assessment (Day 1 cont.) Answer:

217. Subtraction – Fact Learning Summative Assessment (Day 1 cont.) Question # 2 Subtract 4 from 12

218. Subtraction – Fact Learning Summative Assessment (Day 1 cont.) Answer:

219. Subtraction – Fact Learning Summative Assessment (Day 1 cont.) Question # 3 8 cm reduced by 3 cm

220. Subtraction – Fact Learning Summative Assessment (Day 1 cont.) Answer:

221. Subtraction – Fact Learning Summative Assessment (Day 1 cont.) Question # 4 8 kg less 2 kg is how many kg?

222. Subtraction – Fact Learning Summative Assessment (Day 1 cont.) Answer:

223. Subtraction – Fact Learning Summative Assessment (Day 1 cont.) Question # 5 What is 8 km fewer than 14 km?

224. Subtraction – Fact Learning Summative Assessment (Day 1 cont.) Answer:

225. End of Lesson